Field of the Invention
The invention concerns the field of fire-protection glazing, and relates to a fire-protection glazing with a transparent fire-protection layer, which is arranged between two transparent carriers (glass panes for example).
Description of Related Art
With a fire-protection glazing with a fire-protection layer arranged between transparent carriers (in particular glass panes), the side of the glass that faces the fire shatters and a foaming and/or hazing of the fire-protection layer sets in, in the case of a fire. The fire-protection layer then acts in a cooling and/or insulating, which is to say reflecting manner. This fire-protection layer, for example, can be constructed on the basis of silicates or on the basis of hydrogels. Both have their advantages and disadvantages.
A fire-retarding glazing based on hydrogels is described, for example in DE 2713849, with which a space between at least two parallel glass panes is filled with a gel. The gel is formed with the polymerisation of methacrylamide and acrylamide, wherein the polymerisation is effected with the help of peroxides or persalts amid the addition of an accelerating agent (e.g. diethyl amino propionitrile) and, as the case may be, a cross-linking agent (e.g. methylene bisacrylamide, MBA).
DE 10237395 describes a method for manufacturing a fire-protection glazing, wherein a fire-protection composition between two adjacent glass panes is produced. The fire-protection composition forms by way of the polymerisation of acrylic acid and/or methacrylic acid and/or their respective alkali salts and/or ammonium salts of acrylic acid, and a salt solution, a polymerisation initiator and a cross-linking agent are thereby additionally used, wherein alkaline (basic) salt solutions are specified as being preferred.
Hydrogels, which have been known until now are partly constructed from toxic or carcinogenic or mutagenic raw materials (e.g. based on acrylamide/DE 2713849) or raw materials (water-soluble monomers) are used, which preferably polymerise in an alkaline environment. High pH-values however can cause undesirable reactions with glass surfaces (glass corrosion) and thus lead to hazing. A further disadvantage of the hydrogels, which have been applied until now, is their poor adhesion to the glass surface. It is particularly on account of the hydrolysis reactions due to high pH-values that chemical bonding to the glass surface is either destroyed or does not even arise in the first place.
Hydrogels, which are manufactured on the basis of methylolacrylamide, are also known. Methylolacrylamide, for example, can be manufactured from the starting materials of acrylamide and formaldehyde, wherein both starting materials are substances that are hazardous with regard to health. They have been graded as SVHC (substance of very high concern). SVHCs are chemical compounds (or part of a group of chemical compounds) that have been identified as having particularly dangerous characteristics under the REACH stipulations (registration, evaluation, authorisation and restriction of chemicals). For this reason, acrylamide is also classed as being carcinogenic and mutagenic, and formaldehyde is classified as toxic and probably cancer-causing.
An exposure of humans to these substances, for example during production or after the shattering of the fire-protection pane in the case of fire is therefore harmful and should be avoided.
Moreover, a special urgency arises when manufacturing fire-protection glazing based on hydrogels, as soon as the polymerisation initiator is added to the educts of the gel, since the cross-linking and thus the curing of the gel begins immediately. This is particularly disadvantageous if the educts or part of the educts is toxic, since activities carried out in a rush are much more prone to mistakes.